Key supplier closed for business at Easter? Out of office reply saying your contact will be away for a week? Easter is a public holiday in many countries, and business trips to many countries are disrupted by absent counterparts and contacts.

Planning around Easter is tricky for business travellers, since it's a moveable feast and changes date every year -- and the days, times and ways of observing it vary by religion, country and even state or province.

Australian Business Traveller has advice for what you're likely to encounter if you need to deal with business contacts abroad, especially if you're on the road.

When is Easter?

Easter is a moveable feast, and falls each year between March 22 and April 25 in the Western Christian calendar, and between April 4 and May 8 in the Eastern Christian calendar (which covers Orthodox churches in Russia, central Asia, much of Eastern Europe, and Greece).

That means it can fall on different dates in the Western and Eastern branches of Christianity -- this year, Western Easter is on Sunday April 8 while the Eastern calendar celebrates it one week later, on Sunday April 15.

Which countries have public holidays over Easter?

Countries with strong Christian links are likely to celebrate over the full weekend of Easter, with a long weekend that might include one or both of Good Friday (the Friday before Easter Sunday) and Easter Monday (the day after Easter Sunday).

In the UK, both of those days are decreed public or Bank Holidays. The civil service also receives a half day off on Maundy Thursday -- the day before Good Friday. Holidaying around Easter to take advantage of the public holidays is very common, so business is disrupted as a result.

In northern Europe, people often take advantage of the long weekend by booking holidays around it, even in countries that aren't at the top of any list of religious observances.

In Finland, for example, Helsinki nearly shuts down as the urban population heads out to the countryside for a last gasp of winter sport, skiing, sauna and ice-fishing.

Catholic areas -- most of South America, the Philippines, plus Ireland, Portugal, Spain, France, Italy, Poland and southern Germany -- are likely to be away from the office for the full four-day weekend.

In some countries, it also stretches to five days to include Maundy Thursday. In Italy, though, Good Friday is not a public holiday.

New Zealand observes public holidays on Good Friday and Easter Monday. Singapore receives a public holiday for Good Friday, but not Easter Monday. In the United States, there is no public holiday around Easter.